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I have a canon 50d with obstructions on the sensor.

Before any cleaning: Before cleaning

I have tried to clean the filter with this kit.

After cleaning with a blower (All shots at F36, ISO 100, 135MM, of a white sheet of paper): After blower

After first 2 swab wet cleaning (one wet followed by one dry): After 1st wet cleaning

After aggressive wet cleaning, same as above but with multiple passes across the filter and scrubbing one half the filter to see if I could dislodge anything:

After 2nd aggressive wet cleaning

100% crop of the image above: 100% crop

It appears there is granules of sand stuck to the low pass filter and the plastic framing around the sensor: Picture of low pass filter after all cleaning

Here is a cropped view of the top left corner:

Zoomed to show granules stuck to plastic housing as well as filter

Is there a stronger emulsifier I could use on the filter to try to dislodge the granules or another technique I could use to try and remove them?

I have read online about people removing the low pass filters from their cameras so one option might be to remove the filter altogether. The filter has a dust reduction circuitry so this may be more complicated than just removing it Step 17.

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    Wow. Since this camera is from 2008, I think I might consider it a write-off. – mattdm Jan 1 '18 at 21:17
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    are you sure it is sand? – Alaska Man Jan 1 '18 at 21:39
  • @Alaskaman Not sure if it is sand. – Chris Magnuson Jan 1 '18 at 21:46
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    @mattdm The camera's age is also what frees me try a more dangerous repair given that the camera isn't valuable enough to justify a professional repair, but still has life left if I can get this cleaned up :). – Chris Magnuson Jan 1 '18 at 21:48
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    I'd like to see a 100% crop of one of the first four photos. That does not look like sand... Also, do the spots soften up if the aperture is opened up? (What aperture was used for your test shots?) – Michael C Jan 1 '18 at 22:04
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I have observed somewhat similar effect on a scientific CMOS camera. We sent it back to manufacturer, and they suggested that it might have been water condensation.

enter image description here

If that's the case for you, any cleaning that is done externally is not going to help, you need to disassemble the sensor, probably remove glass filter (as you call it, anti-aliasing). But that is not the only filter that sits between environment and semiconductor chip:

enter image description here

Since removing of any of these filters have intrinsic chance of failure q, removing three of them has diminishing chance (1-q)^3 of success. But since camera is throw-away, go ahead and let us know your story!

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Looks like a professional repair job is needed, or you can look into conversion for infra-red (which basically removes the IR cut filter, and perhaps the low-pass filter).

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If you're willing to risk having to write the camera off anyway, you might try very lightly touching it with a loop of cellophane tape (do not press) and see if that helps.

That said, I'd bet there's a decent chance that the reason you can't clean off the particles is that the sand somehow got in behind one of those filter layers, rather than being on the outside.

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